Methoxypyrazine (MP) in minute quantities can greatly affect the vegetative character and overall quality in some wine grape varieties. Results from the past three years show that higher rates of nitrogen and the timing of applications impact MP levels in Cabernet sauvignon and Sauvignon blanc, two important varieties for the BC wine industry. We found that higher rates of nitrogen applied early in the season result in higher levels MP. The primary pyrazine is IBMP which is a bell pepper aroma remains above sensory threshold levels to maturity. We have found that pyrazine level can be altered by up to 40% through manipulating nitrogen applications between bud break and veraison.

Dr. Kevin Usher, Agriculture and Agri-Food Canada, Summerland Research and Development Centre.